This invention relates to valving apparatus, and more particularly, to apparatus wherein the heads of poppet-type valves are movable to positions recessed relative to the cylinder head.
In a generally known type of valve configuration, including poppet valves, the poppet valves include beveled portions which are positionable against seat portions defined by a cylinder head to determine a closed valving state thereof. See, for example, U.S. Pat. Nos. 1,589,441, 2,191,333, 3,209,737, 3,285,235 and 3,563,214. In general, it will be seen in each of these patents that initial movement of a valve to move the head from the seat determines the beginning of the actual effective opening of the valve. In systems of the type disclosed in these patents, it is well known that the initial lifting and final seating of a valve must take place in a relatively gradual manner, i.e., there must not be what would be abrupt openings and closings, since the forces involved for such abrupt openings and closings would be extremely great. Yet, it is also well known that an ideal operation of a poppet valve of the type disclosed would come about if such a valve could be made to snap instantaneously to a full-open position, to stay open for the needed duration, and then to snap closed instantaneously. This is clearly impossible to achieve in practice because infinitely high loads would be necessary to achieve instantaneous lifts. However, it will be understood that it is desirable to approach such an ideal condition, even if the achievement of such ideal condition is not possible.